1. Field of the Invention
The present invention relates to a central car door locking system, and more particularly, to a swing type power door lock actuator.
2. Description of the Related Art
Currently, all cars are equipped with a central door locking system for controlling the locking and unlocking of all the car doors to enhance driver and passenger safety and convenience. Conventional central control car door lock systems (or power door lock actuators) are generally divided into the push-pull type and the swing type. A push-pull type actuator uses an actuating bar (or rod) to push and pull mechanical car door locks between the locking position and the unlocking position. A swing type actuator uses a single swing arm to swing, thereby driving mechanical car door locks between the locking position and the unlocking position. For the advantages of high actuating force, low failure rate and small size for easy installation, swing type actuator has gradually become the standard equipment of major car manufacturing companies.
U.S. Pat. No. 5,441,315 discloses an electric-motor drive for motor-vehicle central lock system, which uses a reversible electric motor to drive an input gear, thereby biasing a support of biasing means. When the support of the biasing means is being biased, a coupling gear is forced into engagement with an output gear, driving the output gear to rotate a threaded output spindle, and thus a nut is forced to move along the threaded output spindle. During movement of the nut along the threaded output spindle, an actuating element is forced by the nut to move a latch between two positions, thereby locking or unlocking the mechanical car door locks. According to this design, when the motor is started up, the rotary driving force must be transmitted through the biasing means for rotating the threaded spindle. The arrangement of the biasing means complicates the structure. Further, any minor installation error of the biasing means can affect the transmission performance. Further, transmission between the nut and the swing arm is achieved by means of matching between a circular block and a U-shaped groove. This arrangement can cause operation inaccuracy of the swing arm due to a manufacturing or installation error. In other words, this prior art patent has the drawbacks of complicated structure, installation difficulty and high failure rate.